Phosphine borines and their preparation



PHOSPHINE BORINES AND THEE PREPARATION Ross I. Wagner, Whittier, Calif., assignor to American Potash & Chemical Corporation, a corporation of Delaware No Drawing. Filed Mar. 2, 1959, Ser. No. 796,293

17 Claims. (Cl. 260-6065) This invention relates in general to phosphine borines and more particularly to phosphine borine compounds formed from various borines and various difunctional phosphines; these phosphine borines may be added to gasoline which may contain tetraethyl lead (TEL) and which will probably contain ethylene dichloride and dibromide (in the case of automotive fuels) and ethylene dibromide alone (in the case of aviation fuels), the phosphine borines serving to reduce preignition of gasoline used as a motor fuel.

It is an object of this invention to provide for the preparation of certain phosphine borines which are particularly useful as preignition additives for gasoline; that is, the new compounds to which this invention is directed serve to reduce preignition of gasoline.

Ancillary objects and advantages of this invention, if not specifically set forth, will become apparent during the course of the description which follows.

Broadly, this invention concerns phosphine borines of the general formula R' BzPR K'R PzBR where each R may be the same or different and represents H or lower alkyl, each R may be the same or different and represents F, Br, Cl, lower alkyl (1-6 carbons) or H, and R" is a lower alkylene group.

These materials may be added to leaded or unleaded gasoline and serve as excellent preignition additives, especially when the said gasoline contains TEL or a similar metal-containing anti-detonant such as methylcyclopentadienyl manganese tricarbonyl, as set forth in greater detail in our co-pending application Serial No. 796,223, filed even date herewith.

When the phosphine borines of this invention are added to motor fuel, the resulting motor fuel is found to have a low preignition index and a high resistance to detonation knocking. Another effect of the use of these phosphine borines is to decrease the tendency of gasoline containing TEL to raise the octane requirement of the engine in which the gasoline is used. A further advantage of these phosphine borines as gasoline additives is that such phosphine borines are highly resistant to hydrolysis, as a result of which they have little tendency to be leached from the fuel by the action of such free water as may be present.

In this respect, the phosphine borines as a class are decidedly advantageous as compared with most other boron-containing gasoline additives which are highly vulnerable to hydrolysis. A further desirable feature of such phosphine borines is that they are liquids or lowmelting solids amply soluble in hydrocarbons. These properties are important in gasoline additives since additives which have high-melting points or low solubilities have a strong tendency to precipitate and form solid deposits when the fuel mixture is vaporized in the carburetor. Such deposits cause malfunctioning of the engine in addition to defeating the purpose of feeding the additive into the combustion chamber. Liquids are also desirable from a material-handling standpoint, since they may be blended conveniently with liquid fuels.

Fatented June 14, 1950 The phosphine borines of the present invention, while highly soluble in hydrocarbons, are relatively insoluble in water; this tends to maintain quantitative requirements at low levels since there is essentially no loss by extraction.

Finally, the fact that halogen may here be introduced in the form of the phosphine borine compound permits a reduction in the amount of ethylene dihalide normally required in leaded gasoline; this enables a reduction in costs by providing means for simultaneously controlling ignition and scavenging lead with a single additive.

Such a phosphine borine, when used as a preignition additive for gasoline, combines the known beneficial effects of both boron and phosphorus in a single molecule of relatively small size and low molecular weight, but,

unexpectedly, small amounts of the phosphine borines are found superior to mixtures of individual commerciallyavailable preigm'tion additives containing phosphorus on the one hand and boron on the other. Further, these phosphine borines are relatively non-reactive and resist decomposition, even at relatively high temperatures.

The range of effective concentrations for these materials and details of their effects upon gasoline will not be further described here, as this information is set out in the afore-mentioned co-pending application.

A general preparative method for these new compounds is as follows: The difunctional phosphine and the boron compound (either diborane or a substituted borine) are introduced into the reaction vessel consecutively. The order of addition does not affect the final product; the choice of which compound is first introduced is dictated by the convenience of handling each or the reagents. If one or both of the reagents is reasonably volatile, the exothermic addition reaction is run under reflux or with external cooling or both to prevent loss of the reagents. For simplicity, the reaction temperature is adjusted to maintain a liquid reaction mixture throughout the synthesis, sometimes requiring external heating. If the product or reactants are thermally unstable at the melting point of the mixture, the synthesis is most conveniently carried out in an inert solvent. Hydrocarbons are the preferred solvent media. The stoichiometry of the reaction calls for 2 moles of the borine for each mole of the difunctional phosphine.

A large number of difunctional phosphines are known; see, for example, co-pending application Serial No. 695,241, filed November 8, 1957, for Phosphines.

The preparation of various boron-containing precursors is described in the literature; see, for exarnple, M. L. Lappert, Organic Compounds of Boron, Chem. Rev., 56, 959 (1956).

Preparation of the various of the boron compounds which may he used in preparing materials of this invention is also set forth in application Serial No. 707,124, filed January 6, 1958 for Organoboron Compounds and application Serial No. 720,067, filed March 10, 1958 for Preparation of Dihaloborines. Still another disclosure of the preparation of these borines is that in application Serial No. 745,248, filed June 30, 1958 for Alkyldihaloborines.

The preparation of various other possible reactants, compounds of the formula ArBX where Ar is an aryl group, is set forth in co-pending application Serial No. 787,106, filed January 16, 1959, for Preparation of Aryldihaloboranes and Poly(dihaloborane) benzenes.

Specific examples are set forth below showing the preparation of the materials of this invention, but these are for illustrative purposes only and are not to be interpreted as imposing limitations on the scope of the invention other than as set forth in the appended claims.

Example 1. Preparation of 1,3-trimethylene-P,P'-bis- (methylphosphine borine).-Into a nitrogen-swept, 250

of 1,3-bis(methylphosphino)propane maintained at 10 C., was added a mixture of diborane and nitrogen. The addition of diborane was'stopped when it appeared in 62 40 (1954). Efficiency of the preignition additive can be measured by the preiguition index which is a percentage of such abnormal flames occurring in the additive- 'the exit gas which passed through a mercury bubbler into containing test gasoline as compared with the base fuel, :a Bunsen burner flame. Excess diboranewas then re i.e., the same TEL-containing gasoline which has not been moved'by degassing the phosphine borine add-uct .under treated with the preignition additive. high vacuum at room temperature. 1 Obviously, many modifications and variations of this 1,3-trimethylene-P,P-bis(methylphosphine borine) is a invention may be made without departing from the spirit colorless solid melting at 28-30 C. The liquid form and scope thereof and therefore only such limitations supercools easily and is metastable at room temperature should be imposed as are indicated in the appended for long periods of time. The supercooled liquid has the claims. following physical properties: density, 0.895 g./rhl. at I Claim 7 25 C.; refractive index, i1 1.5215; miscible with T 1. C mP HH 0f the g n ral formula acetone and benzene, solublein petroleum ether (65-110? H C.') 0.15 g./ 100 g. at 25 C. Vapor tensions in the range R 3B'PR2R RZP'BR 3 determine the equatlon where R" is a lower alkylene group, each R is selected log Pmm.=5.494-2118/T from the class consisting of F, Br, C1, H and lower alkyl, from which the normal boiling point is calculated to be and each R Selected from the class Consisting 9 H '537" C. At temperatures above 150 C. (ca. 3.3 mm. and lower alkylvapor pressure) the compound decomposes with loss of The mmpound of 0131! 1 wherein one R is 0119 hydrogen. 7 R is lower alkyl and each R is H. 7 Example 2. Preparation 0 1,3-trimethylene-P,P'-bis- The compound Of'claim 1 R is H, one '(phosphine b0rine)..-Into a nitrogen-swept, 250 ml. R 15 IOWBY alkyl and each 15 lower l y round-bottom flask containing 26.3 g. 0.243 mole) of The compound of clam 1 w rem each R is H. i1,3-bis(phosphino)propane intermittently cooled in an The compound 2( 2 3 3)2- ice bath, was added a mixture of diborane and nitrogen. Tlle Compound 2( 2 2 3)2- The addition of diborane was stopped when itappeared The Compound 2 2 :2)2 s 2- in the exit gas which passed through a mercury bubbler comPolmds 0f the general formula into a Bunsen burner flame. Excess diborane was then H3B;PR2(CH2)2R2P:BH3 removed by degassing the phosphine borineaddu ct under high vacuum at room temperature. Where each R 15 IOWe! y 1,3-trimethylene-P,P-bis(phosphine borine) is a color- Compounds of the general formula less solid melting at -56" C. The solid is soluble in 35 H B:PR (CH R P:BH petroleum ether (l10 C.) 4.7 g./liter at 25 C. and has vapor tensions in the range 0.5-3.0 mm. determining Where each R 15 alkyl" theequation log Pmm.=l4.49- -5 235/.'Zf from which the Compounds of the general formula normal boiling point is calculated to be 182 C. At tem- R' z( z)4 2 '3 i peratures above 100 C. (ca. 3.6 mm. vapor pressure) 4 i file compound decomposes with loss of hydrogen wherein each R 1s lower alkyl and each R is lower alkyl.

Following the method set forth above, various other ILCompounds of the general m a materials may be prepared; see the table below. R' B;PR (.CH

Ditunctional Phosphine Borine Phesphine Borine Product flfl agz (OH2)2(HOH3P2BH3)2 (CHzMPH onz lrnonsp=nm (CH2)2(PH2)2. 2)2( 2P:BHs)z :)4( H2)n-- (CH2)4(H2P:BH3)Z (CH )1 H CH2 (GfiahPz BHah nnoznennnz As aforementioned, a test for preignition has been devised and the new compounds of this invention'have been compared with other closely related compounds, as a result of which the superiority of these compounds has been made apparent. Briefly, this test involves measuring the number of instances per unit time of motor operation in which flames occur in the combustion chamber prior to the time at which'the normal flame produced by the'spark occurs, in general following theprocedure dewherein each R is lower alkyl and each R is lower alkyl.

12. Compounds of the general formula V Br B PR R"R P BBr iiflo where each R is selected from the class consisting of H where each R is selected from the class consisting of H and lower alkyl. and lower alkyl.

14. Compounds of the general formula 16. The compound (CH [(CH P:BCl C13B:PR2R"R2P:Bc13 17. The compound (CH [(CH P:BBr

where R is a lower alkylene group and each R is selected from the class consisting of H and lower alkyl.

15. Compounds of the general formula C13B I PR2 zRgP I No references cited. 

1. COMPOUNDS OF THE GENERAL FORMULA 